2(1H)-quinolone compounds

ABSTRACT

Compound of formula (I): ##STR1## in which: R 1 , R 2  and R 3 , which are identical or different, represent hydrogen or halogen or alkyl, nitro, cyano or aminosulfonyl, or alternatively, when two of them are located on adjacent carbons, form, with the carbon atoms to which they are attached, (C 3  -C 7 ) cycloalkyl ring or substituted or unsubstituted benzene ring, 
     R 4  represents hydrogen, linear or branched (C 1  -C 6 ) alkyl, substituted or unsubstituted phenyl or a group ##STR2##  in which R 6  and R 7 , which are identical or different, represent hydrogen or substituted or unsubstituted, linear or branched (C 1  -C 6 ) alkyl, 
     R 5  represents hydrogen, hydroxyl, linear or branched (C 1  -C 6 ) alkoxy, phenoxy, mercapto, linear or branched (C 1  -C 6 ) alkylthio, substituted or unsubstituted, linear or branched (C 1  -C 6 ) alkyl, substituted or unsubstituted phenyl or substituted or unsubstituted amino, or a group ##STR3##  in which R 6  and R 7  are as defined above, their isomers as well as their addition salts with a pharmaceutically acceptable acid or base, and medicinal product containing the same are useful as inhibitor of the pathological phenomena associated with hyperactivation of the excitating amino acid-dependant pathways of neurotransmission.

The present application is a division of our prior-filed applicationSer. No. 08/297,793, filed Aug. 30, 1994, now U.S. Pat. No. 5,536,709.

The present invention relates to new 2(1H)-quinolone compounds.

A few 2(1H)-quinolone derivatives have been described in the literature.This applies, for example, to the compounds described by C. ALABASTER etal. (J. Med. Chem., 31, 2048-2056, 1988) which are cardiac stimulators,or to those described by F. BAHR et al. (Pharmazie, 36, H.10, 1981).

The compounds described in the present invention, apart from the factthat they are new, display especially advantageous pharmacologicalproperties: they are potent inhibitors of the phenomena linked to thehyperactivation of excitatory amino acids.

L-Glutamic acid and L-aspartic acid have the capacity to activate theneurons of the central nervous system, and many studies havedemonstrated that these excitatory amino acids (EAA) satisfy thecriteria that define a neurotransmitter. For this reason, the modulationof neuronal events associated with these EAA appears to be anadvantageous target for the treatment of neurological diseases.

In effect, it has been demonstrated that excessive release of EAA andhyperstimulation of their receptors is probably one of the causes of theneuronal degeneration observed in epilepsy, senile dementia or strokes.At the present time, there is an ever-increasing number ofneurodegenerative diseases in which EAA are closely implicated(Huntington's chorea, schizophrenia, amyotrophic lateral sclerosis)(McGEER E. G. et al., Nature 263, 517-519, 1976; SIMON R. et al.,Science 226, 850-852, 1984).

Furthermore, while it is certain that hyperactivation of EAA-dependentneurotransmission exerts neurotoxic effects, the normal activation ofthis neurotransmission facilitates mnemic and cognitive performance(LYNCH G. & BAUDRY M., Science, 224, 1057-1063, 1984; ROTHMAN S. M. &OLNEY J. W., Trends in Neuro Sci., 10, 299-302, 1987). From apharmacological and therapeutic standpoint, it is hence appropriate tocounteract only pathological stimulations while not impairing thephysiological level of activation.

The EAA receptors localized post- and presynaptically have beenclassified in 4 groups in accordance with the affinity and theelectrophysiological an/or neurochemical effects of specific ligands:

NMDA (N-methyl-D-aspartate) receptor associated with an ion channelpermeable to mono- and divalent cations (including calcium) but which isblocked by magnesium. Accumulation of calcium in the cell is consideredto be one of the causes of neuronal death. Opening of the NMDA channelis regulated by several sites associated with the receptor and, inparticular, is promoted by glycine, the effect of which isstrychnine-insensitive. This glycine site constitutes one of theimportant targets for modulating the activation of the NMDA receptor.

AMPA (α-amino-3-(hydroxy-5-methyl-4-isoxazolepropionic acid) receptorassociated with an ion channel permeable to monovalent cations includingsodium. Activation of this channel is considered to bring about amembrane depolarization.

kainate receptor, the ionic characteristics of which are akin to thoseof the AMPA receptor but which differs therefrom by the level ofconductance and desensitization. However, a large number of studies aretending to demonstrate that the AMPA receptor and the kainate receptorhave close structural and functional analogies and constitute a singlereceptor family (KEINANEN K. et al., Science, 249, 556-560, 1990).

ACPD (trans-1-aminocyclopentanedicarboxylic acid) receptor, referred toas a metabotropic receptor since it is not coupled to an ion channel.

Activation of the ionotropic receptors by EAA opens the ion channelsand, in particular, permits the entry of sodium, which depolarizes thecell. This first phase, which involves the AMPA receptor, then leads tohyperactivation of the NMDA receptor and to the massive accumulation ofcalcium (BLAKE J. F. et al., Neurosci. Letters, 89, 182-186, 1988;BASHIR Z. I. et al., Nature 349, 156-158, 1991).

The compounds of the present invention or the products of theirmetabolic hydrolysis (prodrugs) are hence directed, in a novel manner,towards counteracting the excitatory and toxic effects of EAA byblocking the initial activation of the AMPA/kainate receptor.

The compounds of the present invention are hence useful as inhibitors ofthe pathological, in particular neurotoxic, phenomena associated withhyperactivation of the excitatory amino acid-dependent pathways ofneurotransmission. They stand out with respect to products described byEuropean Patent Application EP 542,609 in that they are particularlysoluble in water, are entirely colorless and that they have a goodcerebral bioavailability after systemic administration.

They are hence potential therapeutic agents for the treatment ofneurological and mental diseases involving these amino acids: acute orchronic degenerative diseases, such as stroke, cerebral or spinal traumaor epilepsy or chronic neurodegenerative diseases such as Alzheimer'sdisease, schizophrenia, amyotrophic lateral sclerosis or Huntington'schorea.

More specifically, the present invention relates to the compounds offormula (I): ##STR4## in which: R₁, R₂ and R₃, which are identical ordifferent, represent a hydrogen or halogen atom, a linear or branched(C₁ -C₆) alkyl group (unsubstituted or substituted with one or a numberof halogen atoms) or a nitro, cyano or a aminosulfonyl group, oralternatively, when two of them are located on adjacent carbons, formwith the carbon atoms to which they are attached, a (C₃ -C₇)cycloalkylkene ring or a benzene ring (unsubstituted or substituted withone or a number of halogen atoms or linear or branched (C₁ -C₆) alkyl,linear or branched (C₁ -C₆) alkoxy or trihalomethyl groups),

R₄ represents a hydrogen atom, a linear or branched (C₁ -C₆) alkylgroup, a phenyl group (unsubstituted or substituted with one or a numberof halogen atoms or linear or branched (C₁ -C₆) alkyl, linear orbranched (C₁ -C₆) alkoxy or trihalomethyl groups) or a group ##STR5## inwhich R₆ and R₇, which are identical or different, represent a hydrogenatom or a linear or branched (C₁ -C₆) alkyl group (unsubstituted orsubstituted with a (C₃ -C₇) cycloalkyl or phenyl group),

R₅ represents a hydrogen atom, a hydroxyl, linear or branched (C₁ -C₆)alkoxy, phenoxy, mercapto, linear or branched (C₁ -C₆) alkylthio, linearor branched (C₁ -C₆) alkyl (unsubstituted or substituted with a (C₃ -C₇)cycloalkyl group), phenyl (unsubstituted or substituted with one or anumber of halogen atoms or linear or branched (C₁ -C₆) alkyl, linear orbranched (C₁ -C₆) alkoxy or trihalomethyl groups) or amino(unsubstituted or substituted with one or two linear or branched (C₁-C₆) alkyl groups) group or a group ##STR6## in which R₆ and R₇ are asdefined above, to their isomers as well as to their addition salts witha pharmaceutically acceptable acid or base.

Mention may be made, among pharmaceutically acceptable bases and withoutimplied limitation, of sodium hydroxide, potassium hydroxide,tert-butylamine, diethylamine, ethylenediamine and the like.

The invention also encompasses the process for preparing the compoundsof formula (I), wherein a compound of formula (II): ##STR7## in whichR₁, R₂ and R₃ have the same meaning as in the formula (I), is used asstarting material, which starting material is reduced, depending on thenature of the substituents R₂, R₃ and R₄, either in an aprotic medium inthe presence of lithium aluminum hydride, aluminum hydride, diborane orborane complexes, or in an acidic protic medium when sodiumcyanoborohydride is used, to yield an alcohol of formula (III): ##STR8##in which R₁, R₂ and R₃ have the same meaning as in the formula (I),which is oxidized using a metal oxide in an inert solvent, an alkalimetal hydrohalate in a protic solvent or an acid chloride in dimethylsulfoxide, to yield the aldehyde of formula (IV): ##STR9## in which R₁,R₂ and R₃ have the same meaning as in the formula (I), which is thencondensed with an alkyl malonate of formula (V), in a protic medium, inthe presence of an alkali metal alkoxide, a tertiary amine or an alkalimetal hydroxide: ##STR10## in which alk represents a linear or branched(C₁ -C₆) alkyl group, to yield an ester of formula (VI): ##STR11## inwhich R₁, R₂, R₃ and alk have the same meaning as above, which isconverted to the corresponding acid of formula (VII): ##STR12## in whichR₁, R₂ and R₃ have the same meaning as in the formula (I), which isreacted in the presence of bromine in pyridine to yield the compound offormula (VIII): ##STR13## in which R₁, R₂ and R₃ have the same meaningas in the formula (I), the lactam functional group of which is protectedby reacting with phosphorus oxychloride followed by reacting with analkali metal alkoxide in an alcoholic medium, to yield the compound offormula (IX): ##STR14## in which R₁, R₂ and R₃ have the same meaning asin the formula (I) and R represents a linear or branched (C₁ -C₆) alkylgroup, which is reacted with a dialkyl or a diaryl phosphite in thepresence of triethylamine and tetrakis(triphenylphosphine)palladium ascatalyst, in an anhydrous medium, according to the technique describedby T. HIRAO (Synthesis, 56-57, 1981 ), to yield the compound of formula(X): ##STR15## in which R₁, R₂, R₃ and R have the same meaning as aboveand R'₄ represents a linear or branched (C₁ -C₆) alkyl group or an arylgroup, which is then:

either entirely deprotected in the presence of trimethylsilyl bromide inan acetonitrile medium and then treated in an acidic medium, to yieldthe compound of formula (I/a), a specific case of the compounds offormula (I): ##STR16## in which R₁, R₂ and R₃ have the same meaning asin the formula (I), which is reacted, if desired, in a basic medium witha halogenated derivative of formula R"₄ -Cl in which R"₄ represents alinear or branched (C₁ -C₆) alkyl group, a phenyl group (unsubstitutedor substituted with one or a number of halogen atoms or linear orbranched (C₁ -C₆) alkyl, linear or branched (C₁ -C₆) alkoxy ortrihalomethyl groups) or a group ##STR17## in which R₆ and R₇ have thesame meaning as in the formula (I), to yield the compound of formula(I/b), a specific case of the compounds of formula (I), ##STR18## inwhich R₁, R₂, R₃ and R"₄ have the same meaning as above,

or partially deprotected by treatment in a basic medium to yield thecompound of formula (XI): ##STR19## in which R₁, R₂, R₃, R and R'₄ havethe same meaning as above,

which compound of formula (XI):

is subjected, depending on the nature of the compounds of formula (I)which it is desired to obtain, to:

either: a treatment in an acidic medium to yield the compound of formula(I/c), a specific case of the compounds of formula (I): ##STR20## inwhich R₁, R₂, R₃ and R'₄ have the same meaning as above, oralternatively: the action of an alcohol of formula (XII), according tothe process described by D. A. CAMPBELL (J. Org. Chem., 57, 6331-6335,1992):

    R'.sub.5 --OH                                              (XII)

in which R'₅ represents a phenyl or linear or branched (C₁ -C₆) alkylgroup, to yield the compound of formula (XIII): ##STR21## which isselectively deprotected by reacting with trimethylsilyl bromide in anacetonitrile medium and then treatment with hydrochloric acid, to yieldthe compound of formula (I/d), a specific case of the compounds offormula (I): ##STR22## in which R₁, R₂, R₃ and R'₅ have the same meaningas above,

or yet again: reaction with oxalyl chloride according to the methoddescribed by R. S. RODGERS (Tetrahedron Lett., 33, 7473, 1992), to yieldthe compound of formula (XIV): ##STR23## in which R₁, R₂, R₃, R and R'₄have the same meaning as above,

which compound of formula (XIV) is then treated:

either with an organomagnesium derivative of formula (XV), in ananhydrous medium:

    R".sub.5 MgX                                               (XV)

in which X represents a halogen atom and R"₅ represents a linear orbranched (C₁ -C₆) alkyl group (unsubstituted or substituted with a (C₃-C₇) cycloalkyl group) or a phenyl group (unsubstituted or substitutedwith one or a number of halogen atoms or linear or branched (C₁ -C₆)alkyl, linear or branched (C₁ -C₆) alkoxy or trihalomethyl groups), toyield the compound of formula (XVI): ##STR24## in which R₁, R₂, R₃, R,R'₄ and R"₅ have the same meaning as above, which is deprotected byreacting with trimethylsilyl bromide in an acetonitrile medium and thentreatment with hydrochloric acid, to yield the compound of formula(I/e), a specific case of the compounds of formula (I): ##STR25## inwhich R₁, R₂, R₃ and R"₅ have the same meaning as above,

or which is reacted with a hydride, H₂ S, alkSH (in which alk means alinear or branched (C₁ -C₆) alkyl group) or ammonia, to yield thecompound of formula (XVII): ##STR26## in which R₁, R₂, R₃, R and R'₄have the same meaning as above and R' represents HS--, alkS-- or H₂ N--,or a hydrogen atom, which is deprotected by reacting with trimethylsilylbromide in an acetonitrile medium and then treatment with hydrochloricacid, to yield the compound of formula (I/f), a specific case ofcompounds of formula (I): ##STR27## in which R₁, R₂, R₃ and R' have thesame meaning as above, which compound of formula (I/a), (I/b), (I/c),(I/d), (I/e) or (I/f)

when R₁ and/or R₂ and/or R₃ represent a hydrogen atom, can undergoelectrophilic substitutions according to standard techniques forsubstitution of aromatic ring-systems, yielding a compound of formula(I) mono-, di- or trisubstituted on the phenyl ring of the quinolone,

when R₁ and/or R₂ and/or R₃ represent a nitro group, can undergo ahydrogenation to yield the corresponding amino derivative which, itself,can be, if desired, converted to the corresponding cyano derivative,

can be, if appropriate, purified according to a standard purificationtechnique,

is separated, if appropriate, into its isomers according to a standardseparation technique,

is converted, if desired, to its addition salts with a pharmaceuticallyacceptable acid or base.

The compounds of formula (I) possess very advantageous pharmacologicalproperties. It was possible to study the dual mechanism of action of thecompounds of the present invention by means of membrane bindingtechniques and electrophysiological techniques.

1/ Membrane binding

This is carried out using a rat cortex homogenate. The membrane pelletis prepared in a conventional manner in a sucrose buffer by differentialcentrifugations, and then frozen until used. After thawing, 200 l ofmembrane homogenate are taken up in a Tris-HCl (30 mM), CaCl₂ (2.5 mM)buffer, pH 7.4, and incubated at 4° C. for 30 minutes in the presence of25 μl of [³ H]-AMPA or [³ H]-kainate and 25 μl of the test product.Non-specific binding is determined in the presence of 10 μM quisqualate(AMPA binding) or 10 μM kainic acid (kainate binding). The membranes arethen isolated by filtration. After drying of the filters, theradioactivity is measured by scintillation.

2/ Currents induced by EAA in Xenopus oocytes

Xenopus oocytes are injected with 50 ng of poly(A)⁺ mRNA isolated fromrat cerebral cortex, and incubated for 2 to 3 days at 18° C. to permitprotein expression therein. The inward currents induced by EAA aremeasured in a medium of composition: NaCl (82.5 mM), KCl (2.5 mM), CaCl₂(1 mM), MgCl₂ (1 mM), NaH₂ PO₄ (1 mM), HEPES (5 mM), pH 7.4, by the2-electrode voltage-clamp method (potential=-60 mV). For measurement ofthe currents induced by NMDA and glycine, MgCl₂ is absent from themedium and CaCl₂ is brought to a concentration of 2 mM. The EAA agoniststhat induce the currents are used at the following concentrations:kainate: 100 μm; AMPA: 30 μM; glycine/NMDA: 3/30 μM. The test product isapplied 30 seconds before and during the application of the agonist.

The compounds of the present invention were studied in comparison withthe most recent compounds described for their interaction with the AMPAreceptor: they are 2,3-quinoxalinedione derivatives, and more especially6-cyano-7-nitro-2,3-quinoxalinedione (CNQX) and6-nitro-7-sulfamoylbenzo[f]quinoxaline-2,3-dione (NBQX).

The binding studies showed that the derivatives of the invention bind tothe AMPA receptor with a very advantageous intensity, since the Ki isless than 10⁻⁶ M.

    ______________________________________                                        CNQX               Ki = 0.07 μM                                            Example 2          Ki = 0.9 μM                                             ______________________________________                                    

They are likewise capable of inhibiting the functional activation of thecurrent induced by kainate and AMPA in Xenopus oocytes expressing theglutamate receptors.

    ______________________________________                                        Kainate current                                                                              Example 2   IC.sub.50 = 2 μM                                ______________________________________                                    

This inhibition is strong and constant since the same IC₅₀ (2 μM) isfound with respect to neurotoxic excitatory currents induced in thehippocampus by stimulation of the glutamatergic pathways (Schaeffer'scollaterals).

Although the activity of the compounds of the invention with respect toAMPA/kainate receptors is lower than those of the quinoxalinediones,their therapeutic importance lies in the fact that they exert aselective inhibition of the AMPA receptor without affecting the NMDAreceptor, which frees them from all the side effects described for theNMDA antagonists (psychotomimetic, amnesic and neurotoxic effects).

Furthermore, the compounds of the invention have an in vivo activitywhich is unique and exceptional for the products of this class. In fact,in the audiogenic convulsions test in DBA/₂ mice carried out accordingto the methodology described by CROUCHER et al. (Science, 216, 899,1982), the product of Example 2 counteracts these glutamate-dependentconvulsions and this protective effect is not only observed after IPadministration (ID₅₀ =18.7 mg/kg) but also after oral administration andthe bioavailability index (ID₅₀ IP/ID₅₀ PO) is in the region of 0.3whereas the quinoxalinediones such as CNQX or NBQX do not have anyactivity by the oral route.

The subject of the present invention is also pharmaceutical compositionscontaining as active principle at least one compound of formula (I),alone or in combination with one or more inert, non-toxic excipients orvehicles.

Among the pharmaceutical compositions of the invention, there may bementioned, more especially, those which are suitable for oral,parenteral or nasal administration, simple or sugar-coated tablets,sublingual tablets, hard gelatin capsules, troches, suppositories,creams, ointments, skin gels, and the like.

The appropriate dosage varies according to the patient's age and weight,the nature and severity of the pathology and also the administrationroute. The latter can be oral, nasal, rectal or parenteral. Generallyspeaking, the single doses range between 1 and 1000 mg for a treatmentadministered in 1 to 3 doses per 24 hours.

The examples which follow illustrate the invention and in no way limitit. The starting materials used are known products or products preparedaccording to known procedures.

EXAMPLE 1 5,7-Dichloro-2(1H)-quinolone-3-phosphonic acid

Stage A: 3-Bromo-5,7-dichloro-2(1H)-quinolone

50.8 mmol of bromine are added dropwise to a suspension containing 25.4mmol of 5,7-dichloro-2(1H)-quinolone-3-carboxylic acid in 65 ml ofpyridine at 0 C. After stirring for 10 minutes at room temperature, thewhole mixture is brought to 90 C. for one hour. After cooling, 300 ml of1N hydrochloric acid are added. The expected product is obtained byfiltering the precipitate, then washing the latter with 1N hydrochloricacid and with water and drying.

Melting point: >300° C.

Stage B: 3-Bromo-2,5,7-trichloroquinoline

9.2 mmol of the compound described in the preceding stage are stirredfor 12 hours at reflux in 30 ml of phosphorus oxychloride. Afterevaporating the excess phosphorus oxychloride, the mixture is cooled inan ice bath and then hydrolysed by addition of ice-cold water. Theprecipitate formed is filtered, rinsed with water and dried and yieldsthe expected product.

Melting point: 176°-181° C.

Stage C: 3-Bromo-5,7-dichloro-2-methoxyquinoline

A suspension containing 9 mmol of the compound described in thepreceding stage and 20 ml of a 5.2M methanolic solution of sodiummethoxide is brought to reflux for 12 hours. After cooling, the expectedproduct is obtained after filtering the precipitate.

Melting point: 135°-138° C.

Stage D: Diethyl ester of 5,7-dichloro-2-methoxyquinol-3-ylphosphonicacid

13 mmol of triethylamine, 13 mmol of diethyl phosphite and 0.65 mmol oftetrakis(triphenylphosphine)palladium are added to 6.5 mmol of thecompound described in the preceding stage in suspension in 3 ml ofanhydrous tetrahydrofuran. The whole mixture is brought to reflux, undera nitrogen atmosphere, for 12 hours. The solution is then diluted in 200ml of ethyl acetate. The organic phase is washed with 1N hydrochloricacid and then with a saturated sodium chloride solution. After dryingand evaporation, the expected product is obtained after purifying theresidue by chromatography on a silica column, using as eluent acyclohexane/ethyl acetate (1/1) mixture and then ethyl acetate.

Melting point: 66°-68° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  46.18  4.43       3.85 19.47                                      Found       46.29  4.33       3.95 19.15                                      ______________________________________                                    

Stage E: 5,7-Dichloro-2(1H)-quinolone-3-phosphonic acid

2 ml of trimethylsilyl bromide are added to a solution containing 2 mmolof the compound described in the preceding stage in 10 ml of anhydrousacetonitrile and the whole mixture is stirred for 5 hours at reflux.After evaporation, the residue is taken up in 10 ml of 3N hydrochloricacid, the suspension is stirred for 30 minutes at 80 C. and theprecipitate is filtered. The expected product is obtained afterrecrystallizing the precipitate from ethanol.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  36.76  2.06       4.76 24.12                                      Found       36.58  2.16       4.77 24.18                                      ______________________________________                                    

EXAMPLE 2 6,7-Dichloro-2(1H)-quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 1 by using the corresponding starting material.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  36.76  2.06       4.76 24.12                                      Found       36.82  2.44       4.82 24.65                                      ______________________________________                                    

EXAMPLE 3 Monoethyl ester of 5,7-dichloro-2(1H)-quinolone-3-phosphonicacid

Stage A: Monoethyl ester of 5,7-dichloro-2-methoxyquinol-3-ylphosphonicacid.

1.3 mmol of the compound described in Stage D of Example 1 arevigorously stirred at 100 C. in 5 ml of 5N sodium hydroxide solution for90 minutes. After cooling, the mixture is acidified with 1N hydrochloricacid. After extraction with ethyl acetate, washing the organic phasewith a saturated sodium chloride solution, drying and evaporation, acolorless oil is obtained which slowly crystallizes and yields theexpected product.

Melting point: 157°-158° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  42.88  3.60       4.17 21.10                                      Found       42.95  3.89       4.23 21.13                                      ______________________________________                                    

Stage B: Monoethyl ester of 5,7-dichloro-2(1H)-quinolone-3-phosphonicacid

A suspension containing 2.2 mmol of the compound described in thepreceding stage in 16 ml of 3N hydrochloric acid is stirred for 24 hoursat reflux. The precipitate formed is then filtered and yields theexpected product by recrystallization from isopropanol.

Melting point: 220°-240° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  41.02  3.13       4.35 22.01                                      Found       41.34  3.16       4.47 22.14                                      ______________________________________                                    

EXAMPLE 4 Monoethyl ester of 6,7-dichloro-2(1H)-quinolone-3-phosphonicacid

The expected product is obtained according to the process described inExample 3 by using the corresponding starting material.

Melting point: 268°-276° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  41.02  3.13       4.35 22.01                                      Found       41.28  3.30       4.45 21.84                                      ______________________________________                                    

EXAMPLE 5 5,7-Dichloro-2(1H)-quinolone-3-methylphosphinic acid

Stage A: Ethyl ester of5,7-dichloro-2-methoxyquinol-3-ylmethylphosphinic acid

A solution containing 1.49 mmol of the compound described in Stage A ofExample 3 and 10 l of dimethylformamide in 15 ml of dichloromethane isstirred at 40 C. 3 mmol of oxalyl chloride diluted in 1 ml ofdichloromethane are added dropwise to this solution. The whole mixtureis maintained at 40 C. for one hour and then evaporated under vacuum.The residue is then dissolved in 10 ml of anhydrous tetrahydrofuran and5801 of a 3M solution of methylmagnesium chloride in tetrahydrofuran arethen added dropwise. The reaction mixture is stirred for 90 minutes atroom temperature and then hydrolysed using 1 ml of 1N hydrochloric acid.The whole mixture is diluted in 100 ml of ethyl acetate. The organicphase is washed with 1N hydrochloric acid and then with 1N sodiumhydroxide solution, dried and evaporated. The expected product isobtained after purifying the residue by chromatography on a silicacolumn, using as eluent a dichloromethane/ethanol (97/3) mixture.

Stage B: 5,7-Dichloro-2(1H)-quinolone-3-methylphosphinic acid

The expected product is obtained from the compound described in thepreceding stage according to the process described in Stage E of Example1.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  41.13  2.76       4.80 24.28                                      Found       40.82  2.97       5.01 24.10                                      ______________________________________                                    

EXAMPLE 6 Monoisopropyl ester of6,7-dichloro-2(1H)-quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 3 by using the corresponding starting materials.

Melting point: 235°-238° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  42.88  3.60       4.17 21.10                                      Found       42.19  3.52       4.23 21.22                                      ______________________________________                                    

EXAMPLE 7 Monocyclopentylmethyl ester of6,7-dichloro-2(1H)-quinolone-3-phosphonic acid

Stages A and B:

The processes described in these stages are identical to those describedin Stages A and B of Example 1 from the corresponding starting material.

Stage C: 3-Bromo-6,7-dichloro-2-ethoxyquinoline

The expected product is obtained according to the process described inStage C of Example 1 but replacing the methanolic solution of sodiummethoxide with an ethanolic solution of sodium ethoxide.

Melting point: 56°-58° C.

Stage D: Monomethyl ester of 6,7-dichloro-2-ethoxyquinol-3-ylphosphonicacid

14.3 mmol of triethylamine, 14.3 mmol of dimethyl phosphite and 0.71mmol of tetrakis(triphenylphosphine)palladium are added to a suspensioncontaining 7.1 mmol of the compound described in the preceding stage in5 ml of anhydrous tetrahydrofuran. The whole mixture is stirred atreflux, under nitrogen, for 12 hours. The mixture is then diluted in 200ml of ethyl acetate. The organic phase is washed with 1N hydrochloricacid, then with a saturated sodium chloride solution and finally driedand concentrated to 20 ml. The expected product slowly crystallizes.

Melting point: 164°-166° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  42.88  3.60       4.17 21.10                                      Found       43.37  4.04       3.96 21.31                                      ______________________________________                                    

Stage E: Monocyclopentylmethyl ester of6,7-dichloro-2(1H)-quinolone-3-phosphonic acid

0.42 mmol of cyclopentanemethanol and 0.42 mmol of triphenylphosphineare added to a solution containing 0.28 mmol of the compound describedin the preceding stage in 2 ml of anhydrous tetrahydrofuran. Afterstirring for 10 minutes, 0.42 mmol of diisopropyl azodicarboxylate areadded and the whole mixture is stirred for one hour at room temperature.0.7 mmol of trimethylsilyl bromide are then added dropwise and themixture is stirred for a further one hour at room temperature. Afterevaporation, the residue is taken up in 4 ml of 3N hydrochloric acid andthen stirred for 12 hours at 100° C. After cooling, 20 ml of ethylacetate are added and the two-phase mixture is stirred for 10 minutes.The white suspension which is formed is filtered and yields the expectedproduct.

Melting point: 286°-288° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  47.89  4.29       3.72 18.85                                      Found       47.78  4.38       3.99 18.73                                      ______________________________________                                    

EXAMPLE 86-Chloro-7,8,9,10-tetrahydro-2(1H)-benzo[h]quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 1.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  49.78  4.18       4.47 11.30                                      Found       49.78  4.31       4.48 11.46                                      ______________________________________                                    

EXAMPLE 96-Nitro-7,8,9,10-tetrahydro-2(1H)-benzo[h]quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 1.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  48.16        4.04   8.64                                          Found       48.06        4.14   8.48                                          ______________________________________                                    

EXAMPLE 10 Monoethyl ester of6-nitro-7,8,9,10-tetrahydro-2(1H)-benzo[h]quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 3 from the compound obtained in Stage D of Example 9.

Melting point: 268°-273° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  51.14        4.86   7.95                                          Found       50.92        4.71   7.60                                          ______________________________________                                    

EXAMPLE 11 10-Bromo-2(1H)-benzo[g]quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 1.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  44.10  2.56       3.96 22.57                                      Found       44.36  2.39       4.13 21.09                                      ______________________________________                                    

EXAMPLE 12 7-Nitro-2(1H)-quinolone-3-phosphonic acid

The expected product is obtained according to the process described inExample 1 by using the corresponding starting material.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  40.02        2.61   10.37                                         Found       40.51        2.47   10.07                                         ______________________________________                                    

EXAMPLE 13 Di(pivaloyoxymethyl) ester of6,7-dichloro-2(1H)-quinolone-3-phosphonic acid

7.5 mmol of triethylamine are added to a suspension containing 2.5 mmolof the compound described in Example 2 and the whole mixture is stirredfor approximately 10 minutes at room temperature until completedissolution has taken place. 7.5 mmol of chloromethyl pivalate are addeddropwise to this solution and the reaction mixture is maintainedovernight at 70° C. After returning to room temperature, 100 ml of ethylacetate are added. The precipitate is filtered and rinsed with ethylacetate and the filtrate is washed with 1N hydrochloric acid, then asaturated sodium chloride solution and dried. After evaporating thesolvents under vacuum, the residual colorless oil is taken up in 15 mlof ethyl ether. The expected product then slowly crystallizes.

Melting point: 175° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Cl %                                         ______________________________________                                        Calculated  48.29  5.02       2.68 13.58                                      Found       48.10  4.92       2.75 13.90                                      ______________________________________                                    

EXAMPLE 14 6,7-Difluoro-2(1H)-quinolone-3-phosphonic acid

Stage A: 3-Bromo-6,7-difluoro-2(1H)-quinolone

The expected product is obtained according to the process described inStage A of Example 1 by replacing5,7-dichloro-2(1H)-quinolone-3-carboxylic acid with6,7-difluoro-2(1H)-quinolone-3-carboxylic acid.

Melting point: 265°-271° C.

Stage B: Diethyl ester of 6,7-difluoro-2(1H)-quinolone-3-phosphonic acid

42.2 mmol of triethylamine, 42.2 mmol of diethyl phosphite and 0.25 mmolof tetrakis(triphenylphosphine)-palladium are added to 21.1 mmol of thecompound obtained in the preceding stage in suspension in 100 ml ofanhydrous tetrahydrofuran. The reaction is stirred, at reflux under astream of nitrogen, until the solvent has completely evaporated. Theresidue is then taken up in ethyl acetate. The solid formed is filtered,suspended in water and the whole mixture is stirred for 10 minutes. Theexpected product is obtained by filtration and drying.

Melting point: 245°-252° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  49.22        4.45   4.42                                          Found       49.07        4.10   4.56                                          ______________________________________                                    

Stage C: 6,7-Difluoro-2(1H)-quinolone-3-phosphonic acid

The expected product is obtained according to the process described inStage E of Example 1 from the compound obtained in the preceding stage.

Melting point: 290°-297° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  41.40        2.32   5.36                                          Found       40.77        2.27   5.26                                          ______________________________________                                    

EXAMPLE 15 6,7-Diethyl-2(1H)-quinolone-3-phosphonic acid

Stage A: 3,8-Dibromo-6,7-dimethyl-2(1H)-quinolone

55.2 mmol of bromine are added dropwise to a suspension containing 9.2mmol of 6,7-dimethyl-2(1H)-quinolone-3-carboxylic acid in 15 ml ofpyridine brought to 70° C. After cooling, the whole mixture is pouredinto 1N hydrochloric acid. The aqueous phase is extracted with ethylacetate. The organic phase is dried, evaporated and yields the expectedproduct which is purified by chromatography on a silica column, using aseluent a cyclo-hexane/ethyl acetate (1/1) mixture, then ethyl acetateand finally an ethyl acetate/methanol (98/2) mixture.

Melting point: 216°-223° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Br %                                         ______________________________________                                        Calculated  39.92  2.74       4.23 48.28                                      Found       40.35  2.72       4.24 48.21                                      ______________________________________                                    

Stage B: Diethyl ester of8-bromo-6,7-dimethyl-2(1H)-quinolone-3-phosphonic acid

The expected product is obtained according to the process described inStage B of EXample 14 from the compound described in the precedingstage.

Melting point: 187°-195° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %  H %        N %    Br %                                         ______________________________________                                        Calculated  46.41  4.93       3.61 20.58                                      Found       46.54  4.87       3.61 20.84                                      ______________________________________                                    

Stage C: Diethyl ester of 6,7-dimethyl-2(1H)-quinolone-3-phosphonic acid

2.5 mmol of the compound obtained in the preceding stage arehydrogenated at room temperature in 80 ml of ethanol in the presence of150 mg of palladium-on-charcoal (5%). After filtering the catalyst andevaporation, the residue is taken up in dichloromethane. The organicphase is washed with water, dried and evaporated and yields the expectedproduct.

Melting point: 165°-170° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  58.25        6.52   4.53                                          Found       58.16        6.50   4.51                                          ______________________________________                                    

Stage D: 6,7-Dimethyl-2(1H)-quinolone-3-phosphonic acid

The expected product is obtained according to the process described inStage E of Example 1 from the product described in the preceding stage.

Melting point: >300° C.

    ______________________________________                                        Elemental microanalysis:                                                                C %        H %    N %                                               ______________________________________                                        Calculated  52.18        4.78   5.53                                          Found       52.05        4.81   5.60                                          ______________________________________                                    

Pharmacological study of the derivatives of the invention

In vivo Neuroprotective effects

1) Transient global cerebral ischemia in Gerbil

Transient and complete arrest of cerebral blood flow which is observedin clinical situation during a cardiac infarct, gives rise to a delayeddeath of specific vulnerable neurons, especially in hippocampus, acrucial cerebral region for cognitive functions. This phenomenon can beexperimentally reproduced after transient occlusion of common carotidarteries.

In Gerbil, a transient occlusion (5 minutes) of carotid arteries givesrise to a total loss of hippocampal pyramidal neurons (CA1). This deathcan be observed only 3 or 4 days after ischemia. Numerous studies haveshown that it could be due essentially to an excessive release ofglutamate during the post-ischemic reperfusion.

Neuroprotective effects of anti-ischemic drugs can be demonstrated byhistological measurement of the number of survival neurons.

NBQX (30 mg/kg IP) protects 50% of neurons in case of treatment 30minutes before then b.i.d. after ischemia until histological measurement4 days later.

In the same conditions, compound of example 2 (30 mg/kg IP) protectscompletely from neuronal death and at a smaller dose (10 mg/kg IP)protects 50% of hippocampal neurons.

2) Permanent focal ischemia in mice

In Man, the occlusion of sylvian artery (middle cerebral artery) is thecause of 70-80% of stroke cases.

This ischemia can be perfectly reproduced in mice by electrocoagulationof MCA, giving rise to a well delimited cortical infarct 24 hours later.This infarct can be easily measured by histological examination.

At 30 mg/kg IP administered before then 3 hours after ischemia, NBQX andcompound of example 2 decrease significantly the infarct volume (-26%).

With the same dose administered only in curative manner (5 minutes, 1hour and 2 hours after MCA occlusion), the compound of example 2decreases the infarct volume (-23%) and on the contrary NBQX remainsineffective.

EXAMPLE 17 Pharmaceutical composition

    ______________________________________                                        Preparation formula for 1000 tablets containing a dose of 10                  ______________________________________                                        mg                                                                            Compound of Example 2                                                                              10     g                                                 Hydroxypropylcellulose                                                                             2      g                                                 Wheat starch         10     g                                                 Lactose              100    g                                                 Magnesium stearate   3      g                                                 Talc                 3      g                                                 ______________________________________                                    

We claim:
 1. A method for treating cerebral ischemia in a mammal,comprising the step of administering to the mammal an amount of acompound selected from those of formula (I): ##STR28## in which: R₁, R₂,and R₃, which are identical or different, represent hydrogen, halogen,linear or branched (C₁ -C₆) alkyl which is unsubstituted or substitutedwith one or a number of halogen atoms or nitro, cyano, or aminosulfonylgroups,or alternatively, when two of R₁, R₂, and R₃, are located onadjacent carbons, form, with the carbon atoms to which they areattached, a (C₃ -C₇) cycloalkene ring or a benzene ring which isunsubstituted or substituted with one or a number of halogen atoms orlinear or branched (C₁ -C₆) alkyl, linear or branched (C₁ -C₆) alkoxy,or trihalomethyl groups, R₄ represents hydrogen, linear or branched (C₁-C₆) alkyl, phenyl which is unsubstituted or substituted with one or anumber of halogen atoms or linear or branched (C₁ -C₆) alkyl, linear orbranched (C₁ -C₆) alkoxy, or trihalomethyl, or a group ##STR29## inwhich R₆ and R₇, which are identical or different, represent a hydrogenatom or linear or branched (C₁ -C₆) alkyl, which is unsubstituted orsubstituted with (C₃ -C₇) cycloalkyl or with phenyl, R₅ representshydrogen, hydroxyl, linear or branched (C₁ -C₆) alkoxy, phenoxy,mercapto, linear or branched (C₁ -C₆) alkylthio, linear or branched (C₁-C₆) alkyl which is unsubstituted or substituted with (C₃ -C₇)cycloalkyl, phenyl which is unsubstituted or substituted with one or anumber of halogen atoms or with linear or branched (C₁ -C₆) alkyl,linear or branched (C₁ -C₆) alkoxy, or trihalomethyl, or amino which isunsubstituted or substituted with one or two linear or branched (C₁ -C₆)alkyl, or a group ##STR30## in which R₆ and R₇ are as defined above, itsisomers, and its addition salts with a pharmaceutically-acceptable acidor base, which is effective for alleviation of said condition.
 2. Themethod of claim 1 wherein at least one of the groups R₁, R₂, and R₃represents chlorine.
 3. The method of claim 1 wherein R₄ representshydrogen.
 4. The method of claim 1 wherein R₅ represents hydroxyl. 5.The method of claim 1 wherein the compound is6,7-dichloro-2(1H)-quinolone-3-phosphonic acid.
 6. The method of claim1, wherein an effective amount of the compound is administered inadmixture with one or more pharmaceutically-acceptable excipients orvehicles.
 7. The method of claim 1 wherein the compound is6-chloro-7,8,9,10-tetrahydro-2(1H)-benzo[h]quinolone-3-phosphonic acid.8. The method of claim 6 wherein the compound is6-nitro-7,8,9,10-tetrahydro-2(1H)-benzo[h]quinolone-3-phosphonic acid.9. The method of claim 1 wherein the compound is monoethyl ester of6-nitro-7,8,9,10-tetrahydro-2(1H)-benzo[h]quinolone-3-phosphonic acid.